Carbon disk rheostat



Jan. 22, 1935. G. o. WlLMS CARBON DISK RHEOSTAT Original Filed July 13, 1922 Patented Jan. 22, 1935 UNITED STATE-S PATENT OFFICE CARBONVVDISIK Rnsos'm'r Gustav o. Wilma, Milwaukee, 'wis, assignor, by mesne' assignments, to Allen-Bradley Company, 7 'Milwaukee,,Wis., a; corporation .of Wisconsin a Claims.

This invention relates to'a. carbon disk rheostat.

The present application is a division of application Serial No. 574,803, filed July '13, 1922, Patent *No. 1,631,111, May 31, 1927.

The invention is illustrated hereinas applied to a. rheostat such as set forth in the original appli cation.

The object of the invention isto provide a carbon disk rheostatin which the disks are retained in contact under a minimum initial pressure before the actuator applies pressure thereto.

Another object is to provide a carbon disk rheostat in which the initial pressure upon the disks may be adjusted.

According to the present invention, the rheostat comprises a carbon disk or other compressible resistor, an actuator to vary the pressure upon said resistor, and means to-retain the disks in contact under a minimum initial pressure before theactuator appliespressure thereto.

The invention may be employed in various carbon disk rheostats and applied thereto in different ways.

The accompanying drawing illustrates a rheostat in which the invention is applied, and the views therein are as follows:

Fig. 1 is a sectional side view, and

Fig. 2 is a sectional view on the line 22 of Fig. 1.

The rheostat has two carbon disk resistors 1, a low tension resistor spring 2 to control the pressure applied thereto, and a screw actuator 3 to deflect said spring and thereby vary its tension to vary the pressure upon the resistors.

The resistors are arranged in an insulating casing or holder 4 which has a cover 5 fastened thereto by rivets and provided with lugs 6 for attaching the rheostat to a support.

The spring 2 also functions as a bridge bar to connect the resistors l in series and is provided at the center thereof with an aperture in which the inner end 7 of the actuator 3 is journaled.

The actuator 3 is threaded in a sleeve 8 carried by the cover 5 and is provided with an operating knob 9 for rotating the actuator to vary the tension of the spring 2.

The casing carries binding terminals 10 by which the resistors are connected in circuit.

The carbon disks are retained in contact under a minimum initial pressure before pressure is applied thereto by the actuator by a low tension adjusting spring 11 which acts through a rod 12 and an insulating cross bar 13.

The resistors each have a pressure plate 14 provided with a stud which passes through the cross and thereby retains the carbon disks in initial 15 contact.

The adjusting spring is arranged upon the rod between a nut'l5 and the casing and. its tension may be varied by turning the nut to adjust the initial pressure upon the disks.

'When the rheostat is in service the circuit extends from the terminals 10 through the resistors 1 and across the resistor spring.

The cross bar 13 may be made of insulating material and the resistors 1 connected in series solely by the spring 2 and removed from circuit by retracting the actuator 3 to move the spring 2 out of contact with the pressure plates 14.

Theresistors have the circuit thereof opened and closed by the resistor spring being operated by the actuator to be engaged therewith or disengaged therefrom.

Inasmuch as the resistor spring has a low tension, at low pressure may be varied upon the resistors to obtain a slow and gradual variation in resistance through a wide range as set forth in the original application.

The invention set forth herein may be employed in various rheostats and the spring may have different forms and be applied in different ways.

The invention is hereby claimed as follows:

1. A controller comprising two compressible resistors arranged parallel to each other, a bridge bar to connect said resistors in series, an actuator to apply and vary pressure upon said bridge bar to vary the resistance of said resistors, and a cross bar to apply an initial low pressure upon said resistors independently of said actuator, and a spring to control the pressure exerted by said cross bar.

2. A controller comprising two compressible resistors arranged parallel to each other, a bridge bar to connect said resistors in series, an actuator to apply and vary pressure upon said bridge bar to vary the resistance of said resistors, a cross bar engaging said resistors, a rod connected to said cross bar and arranged between said resistors, and an adjustable spring connected to said rod to cause said cross bar to apply an initial low pressure upon said resistors.

3. A controller comprising two compressible resistors arranged parallel to each other and connected in circuit in series, a low tension spring to apply and vary a low pressure upon said repressure thereon, an actuator connected to said bridge and operable to apply pressure thereon to vary the resistance of said resistors and to retract said bridge out of contact with said resistors to remove the same from circuit, and means independent of said actuator and said bridge to apply an initial low pressure upon said resistors to hold the disks thereof in contact with each other before pressure is applied to said resistors by said bridge and adjustable to vary said initial low pressure.

5. A controller, comprising two compressible resistors arranged parallel to each other, a low tension spring to connect said resistors in circuit and to apply pressure thereon, an actuator connected to said spring and operable to apply pressure thereon to vary the resistance of said resistors and to retract said spring out of contact with said resistors to remove the same from circuit, and means independent of said actuator and said spring to apply an initial low pressure upon said resistors to hold the disks thereof in contact with each other before pressure is applied to said resistors by said spring andadjustable to vary said initial low pressure.

6. A rheostatic controller comprising two carbon disk resistors arranged parallel to each other, a bridge to apply pressure upon said resistors and open and close the circuit therethrough, an actuator to operate said bridge to vary the pressure upon said resistors, a cross bar arranged to retain the disks in said resistors in contact and apply an initial pressure to said resistors before pressure is applied thereto by said bridge, and a spring arranged to cause said cross bar to apply said initial pressure to said resistors.

7. A rheostatic controller comprising two carbon disk resistors arranged parallel to each other, a bridge to apply pressure upon said resistors and open and close the circuit therethrough, an actuator to operate said bridge to vary the pressure upon said resistors, a cross bar arranged to retain the disks in said resistors in contact and apply an initial pressure to said resistors before pressureis'applied; thereto by said bridge, and a spring arrangedto cause said cross bar to apply said initial pressure to said resistors and having its tension adjustable.v

8. A rheostatic controller comprising two carbon disk resistors arranged parallel to each other,

a low tension spring to apply pressure upon said resistors and open and close the circuit therethrough, an actuator to operate said low tension spring to vary the pressure-upon said resistors, a cross bar arranged to retain the disks in said resistors in contact and apply an initial-pressure to said resistors before'pressure is applied there to by-said low tension spring, and a spring arranged to cause said cross bar to apply said ini'-,

tial pressure to said resistors.

9. A rheostatic controller comprising two carbon disk resistors'arranged parallel to each other, a low tension spring to apply pressure upon said resistors and open and close the circuit there 

